The aim of the present study was to determine the value of tonsillectomy in the initial diagnostic work-up of head and neck squamous cell carcinoma of unknown primary (HNSCCUP).

A single-center retrospective study (1999–2012) included 45 patients. All cases underwent physical examination, panendoscopy and contrast-enhanced neck and chest CT scan; 27 (60%) also underwent 18-FDG PET scan. Imaging was systematically performed before panendoscopy. In 34 cases (75%), histologic tonsil samples ipsilateral to the HNSCCUP were collected (28 tonsillectomies and 6 biopsies) during panendoscopy. Categoric variables were compared on Chi-square test.

Clinical examination and CT did not identify any primary tumor. In 13 cases (38%), invasive squamous cell carcinoma (SCC) was diagnosed on histological samples (12 tonsillectomies, 1 biopsy). For these 13 cases, lymph nodes were located in the upper or middle jugular group, and in 3 cases lymph nodes were cystic on CT scan. In 7 cases (26%), there was an abnormal tonsillar 18-FDG uptake ipsilateral to the cervical lymphadenopathy; tonsillectomy was performed, and SCC was found in 5 of these cases: i.e., 18-FDG PET showed sensitivity and specificity of respectively 55.5 and 88.8%.

Tonsillectomy has a role in the initial diagnostic work-up of HNSCCUP. It is especially useful when lymph nodes are located in the upper and/or middle jugular group with a cystic aspect on CT.